From Doug Altman’s paper “How to obtain the confidence interval from a P value” BMJ 2011;343:d2090 Steps to calculate CI for a difference Est from p-value calculate the test statistic for a normal distribution test, z, from p: calculate the standard error: (ignoring minus signs) calculate the 95% CI: …

# Tag: p-value

## Does the p-value overestimate the strength of evidence?

Thom Baguley points to the standardized or minimum LR (p381) to answer this question. The minimum LR represents a worst case scenario for the null in that it compares the LR for against the MLE of the observed data, i.e. the most likely (strongest) possible hypothesis supported by the data, and is defined as …

## Classical statistical inference and its discontents

“Classical” statistical inference in medicine is usually synonymous with frequentist inference, the central element of which is the null hypothesis significance testing (NHST). Even though that was not its original intent, NHST is in practice used to evaluate the evidence for or against a hypothesis, due to confusion in mixing Fisher’s approach with that of…